1. Field of the Invention
The invention relates to a process and an apparatus for the punching and removal of the sprue in a two-part injection molding tool, particularly to a process for manufacturing information carrying disks by injecting synthetic thermoplastic material into a cavity of a two-part molding tool and punching the resulting sprue by axially displacing parts of the molding tool.
The configuration of the sprue cavity serves to deflect by 90.degree. the liquid synthetic plastic arriving from a runner of the machine nozzle and introduce the plastic to the mold cavity uniformly over the circumference of the cavity. A sprue formed in the sprue cavity during the injection molding process must be cut from the molded product and removed after a cooling phase.
2. Description of the Prior Art
West German DE-OS No. 28 38 634 shows using an ejector to separate a sprue from a single piece annular injection molding by punching the sprue from the molding.
The punching and ejector apparatus is placed in part of an essentialy two-part mold opposite to a part of the mold with an injection nozzle. The punching apparatus consists of an annular mold part and a punch, the terminal section of which separates the sprue from the annular part in cooperation with the mold part. In this process the two-part injection molding tool or injection mold is opened, by moving the two parts of the mold apart from each other. The separation of the two mold parts is effected in two steps. Initially, to the extent only that the sprue held, an undercut is punched in the free space created by means of a hydraulically actuated tubular ejector, where it is still being held by means of the undercut in its axial position. The mold is then opened completely and the sprue ejected by means of an ejector pin guided in a tubular ejector from the undercut, so that it drops downward in the parting plane of the injection molding tool.